Independent analysis puts a WXT exenatide lot at 96.5%, against 92.6% on the certificate

A peptide content determination commissioned by the Journal on a 2 mg exenatide vial from WXT has returned 94% of the labelled mass. Chromatographic purity on the same vial was above 96.5%. The two numbers measure different things and only one of them was on the certificate.

Content by elemental nitrogen determination returned 94% of the labelled nominal mass, which on a 2 mg vial corresponds to roughly 7.94 mg of peptide rather than the labelled figure. The remainder is accounted for by counter-ion, residual water and residual solvent, none of which is visible chromatographically.

The wider context is that material sold for research use carries no regulatory release specification in any jurisdiction the Journal has examined. A certificate is a commercial document, not a compliance one, and its content is whatever the issuer chooses to put on it. That is the gap independent testing fills, and it fills it imperfectly.

Yusuf Kandemir, freight and customs broker, Istanbul, was more cautious. "One lot tells you about one lot. I would not draw a conclusion about a company from a single determination, and I would not let a company draw one either."

WXT’s dossier has been updated with this determination and with the date of the request for comment. The dossier’s "what we could not verify" box records the questions still outstanding.